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<a href="cong__ctl_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="preprocessor">#include &quot;<a class="code" href="detail_2net__flow__fwd_8hpp.html">flow/net_flow/detail/net_flow_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="preprocessor">#include &quot;<a class="code" href="peer__socket_8hpp.html">flow/net_flow/peer_socket.hpp</a>&quot;</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="preprocessor">#include &quot;<a class="code" href="options_8hpp.html">flow/net_flow/options.hpp</a>&quot;</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="preprocessor">#include &quot;<a class="code" href="util_2util_8hpp.html">flow/util/util.hpp</a>&quot;</span></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="preprocessor">#include &quot;<a class="code" href="log_8hpp.html">flow/log/log.hpp</a>&quot;</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="preprocessor">#include &lt;map&gt;</span></div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span><span class="preprocessor">#include &lt;iostream&gt;</span></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="preprocessor">#include &lt;boost/weak_ptr.hpp&gt;</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span> </div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1net__flow.html">flow::net_flow</a></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span>{</div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment"></span> </div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment">/**</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> * The abstract interface for a per-socket module that determines the socket&#39;s congestion control</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> * behavior.  Each Peer_socket is to create an instance of a concrete subclass of this class,</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> * thus determining that socket&#39;s can-send policy.</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> *</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> * ### Congestion control ###</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> * This term refers to the process of deciding when to send data, assuming data are available</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> * to send.  In a magic world we could send all available data immediately upon it becoming</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> * available, but in the real world doing so at a high volume or in poor networks will eventually</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> * lead to packets being dropped somewhere along the way or at the destination.  To determine</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment"> * whether we can send data (if available), we maintain `m_snd_flying_bytes` (how much we think is</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"> * currently In-flight, i.e. sent by us but not yet Acknowledged by the receiver or Dropped by the</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment"> * network or receiver) and CWND (how much data we think the route, or pipe, can hold In-flight</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment"> * without dropping too much).  Basically if Peer_socket::m_snd_flying_bytes &lt; CWND, data could be sent.</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment"> *</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment"> * How to determine CWND though?  That is the main question in congestion control.  In `net_flow`,</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment"> * the Peer_socket data member `Congestion_control_strategy sock-&gt;m_cong_ctl` provides the API that</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment"> * returns CWND (how it does so depends on the real type implementing that interface).  In order to</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment"> * compute/update CWND, Congestion_control_strategy and all subclasses have `const` access to `sock`.</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment"> * Since it does not get its own thread, it needs to be informed of various events on `sock` (ACKs,</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment"> * timeouts) so that it can potentially recompute its CWND.  Thus the interface consists of,</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment"> * basically: congestion_window_bytes() (obtain CWND for comparison to In-flight bytes in</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment"> * `can_send()`); and `on_...()` methods to effect change in the internally stored CWND.</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment"> *</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment"> * ### Object life cycle ###</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"> * There is a strict 1-to-1 relationship between one Congestion_control_strategy</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment"> * instance and one Peer_socket.  A Congestion_control_strategy is created shortly after Peer_socket</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment"> * is and is saved inside the latter.  Conversely a pointer to the Peer_socket is stored inside the</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment"> * Congestion_control_strategy.  Many congestion control algorithms need (read-only) access to the</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment"> * innards of a socket; for example they may frequently access Peer_socket::m_snd_smoothed_round_trip_time</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment"> * (SRTT) for various calculations.  The containing Peer_socket must exist at all times while</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"> * Congestion_control_strategy exists.  Informally it&#39;s recommended that Peer_socket destructor or</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment"> * other method deletes its Congestion_control_strategy instance when it is no longer needed.</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment"> *</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"> * ### Functionality provided by this class ###</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment"> * The main functionality is the aforementioned interface.</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> *</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> * Secondarily, this main functionality is implemented as do-nothing methods (as opposed to pure</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> * methods).  Finally, the class stores a pointer to the containing Peer_socket, as a convenience</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> * for subclasses.</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment"> *</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment"> * ### General design note ###</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span><span class="comment"> * TCP RFCs like RFC 5681 tend to present a monolithic congestion</span></div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span><span class="comment"> * control algorithm.  For example, Fast Retransmit/Fast Recovery is described as one combined</span></div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="comment"> * algorithm in RFC 5681-3.2.  It doesn&#39;t describe loss detection (3 dupe-ACKs), retransmission</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span><span class="comment"> * (send first segment found to be lost), congestion window adjustment and loss recovery</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="comment"> * (CWND/SSTHRESH halving, CWND inflation/deflation) as belonging to separate modules working</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="comment"> * together but rather as one monolithic algorithm.  The design we use here is an attempt to</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span><span class="comment"> * separate those things into distinct modules (classes or at least methods) that work together but</span></div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span><span class="comment"> * are abstractly separated within reason.  This should result in cleaner, clearer, more</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="comment"> * maintainable code.  Namely, retransmission and loss detection are (separate) in Node, while CWND</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment"> * manipulations are in Congestion_control_strategy.  Congestion_control_strategy&#39;s focus is, as</span></div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment"> * narrowly as possible, to compute CWND based on inputs from Node.  This may run counter to the</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment"> * how a given RFC is written, since the part of &quot;Reno&quot; involving counting dupe-ACKs is not at all</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment"> * part of the Reno congestion control module (Congestion_control_classic) but directly inside Node</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment"> * instead.</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment"> *</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment"> * ### Assumptions about outside worl###</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment"> * To support an efficient and clean design, it&#39;s important to</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment"> * cleanly delineate the level of abstraction involved in the Congestion_control_strategy class</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment"> * hierarchy.  How stand-alone is the hierarchy?  What assumptions does it make about its underlying</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment"> * socket&#39;s state?  The answer is as follows.  The hierarchy only cares about</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment"> *</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment"> *   1.  events (`on_...()` methods like on_acks()) that occur on the socket (it must know about EVERY</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment"> *       occurrence of each event as soon as it occurs);</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment"> *   2.  certain state of the socket (such as Peer_socket::m_snd_flying_bytes).</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment"> *</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment"> * The documentation for each `on_...()` method must therefore exactly specify what the event means.</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment"> * Similarly, either the doc header for the appropriate method or the class doc header must</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment"> * specify what, if any, Peer_socket state must be set and how.  That said, even with clean</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment"> * documentation, the key point is that the Congestion_control_strategy hierarchy must work TOGETHER</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment"> * with the Node and Peer_socket; there is no way to make the programmer of a congestion control</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment"> * module be able to ignore the relevant details (like how ACKs are generated and</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment"> * handled) of Node and Peer_socket.  The reverse is not true; congestion control MUST be a black</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment"> * box to the Node code; it can provide inputs (as events and arguments to the `on_...()` calls; and</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment"> * as read-only state in Peer_socket) to Congestion_control_strategy objects, but it must have no</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment"> * access (read or write) to the latter&#39;s internals.  This philosophy is loosely followed in the</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment"> * Linux kernel code, though in my opinion Linux kernel code (in this case) is not quite as</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment"> * straightforward or clean as it could be (which I humbly tried to improve upon here).  Bottom line:</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span><span class="comment"> *</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment"> *   1.  Congestion_control_strategy and subclasses are a black box to Node/Peer_socket code (no</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment"> *       access to internals; access only to constructors/destructor and API).</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment"> *   2.  Congestion_control_strategy and subclasses have `const` (!) `friend` access to Peer_socket</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment"> *       internals.</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment"> *   3.  The programmer of any Congestion_control_strategy subclass must assume a certain event</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment"> *       model to be followed by Node.  This model is to be explicitly explained in the doc headers</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment"> *       for the various `on_...()` methods.  Node must call the `on_...()` methods as soon as it</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment"> *       detects the appropriate events, and it should aim to detect them as soon as possible after</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment"> *       they occur.</span></div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment"> *   4.  The programmer of any Congestion_control_strategy subclass may assume the existence</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment"> *       and meaning of certain state of Peer_socket, which she can use to make internal</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment"> *       computations.  Any such state (i.e., in addition to the on-event calls, and their</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span><span class="comment"> *       arguments, in (3)) must be explicitly documented in the class or method doc headers.</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span><span class="comment"> *</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span><span class="comment"> * ### Choice of congestion window units ###</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span><span class="comment"> * We choose bytes, instead of multiples of max-block-size (in</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="comment"> * TCP, this would be maximum segment size [MSS]).  Either would have been feasible.  TCP RFCs use</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment"> * bytes (even if most of the math involves incrementing/decrementing in multiples of MSS); so does</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment"> * at least the canonical BSD TCP implementation (Stevens/Wright, TCP/IP Illustrated Vol. 2) from</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span><span class="comment"> * the early 90s (not sure about modern version).  Linux TCP uses multiples of MSS, as do many</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span><span class="comment"> * papers on alternative congestion control methods.  Reasoning for our choice of bytes: First, the</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span><span class="comment"> * particular congestion control implementation can still do all internal math in multiples of</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="comment"> * max-block-size (if desired) and then just multiply by that in congestion_window_bytes() at the</span></div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span><span class="comment"> * last moment.  Second, I&#39;ve found that certain algorithms, namely Appropriate Byte Counting, are</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span><span class="comment"> * difficult to perform in terms of multiples while staying true to the algorithm as written (one</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span><span class="comment"> * either has to lose some precision or maintain fractional CWND parts which cancels out some of the</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span><span class="comment"> * simplicity in using the multiples-of-MSS accounting method).  Thus it seemed natural to go with</span></div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment"> * the more flexible approach.  The only cost of that is that Node, when using</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment"> * congestion_window_bytes(), must be ready for it to return a non-multiple-of-max-block-size value</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment"> * and act properly.  This is not at all a major challenge in practice.</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment"> *</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment"> * ### Terminology ###</span></div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment"> * In doc comments throughout this class hierarchy, the terms &quot;simultaneously,&quot;</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment"> * &quot;immediately,&quot; and &quot;as soon as&quot; are to be interpreted as follows: Within a non-blocking amount of</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment"> * time.  Note that that is not the same as literally &quot;as soon as possible,&quot; because for efficiency</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment"> * the Node implementation may choose to perform other non-blocking actions first.  For example,</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment"> * on_acks() is to be called &quot;as soon as&quot; a packet acknowledgment is received, but the Node can and</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment"> * should first accumulate all other acks that have already arrived, and only then call on_acks()</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment"> * for all of them.  Thus, in practice, in the `net_flow` implementation, &quot;immediately/as soon</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment"> * as/simultaneously&quot; is the same as &quot;within the same boost.asio handler invocation,&quot; because each</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment"> * handler is written to complete without blocking (sleeping).</span></div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span><span class="comment"> *</span></div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span><span class="comment"> * ### Thread safety ###</span></div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment"> * Unless stated otherwise, a Congestion_control_strategy object is to be accessed</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment"> * from the containing Peer_socket&#39;s Node&#39;s thread W only.</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment"> *</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment"> * How to add a new Congestion_control_strategy subclass?  First write the code to above spec (using</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment"> * existing strategies as a basis -- especially Congestion_control_classic, upon which most others</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment"> * are usually based) and put it in the self-explanatory location.  Next, add it to the socket</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment"> * option machinery, so that it can be programmatically selected for a given Node or Peer_socket,</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment"> * or selected by the user via a config file or command line, if the application-layer programmer so</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span><span class="comment"> * chooses.  To do so, add it to the following locations (by analogy with existing ones):</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment"> *</span></div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment"> *   - `enum Peer_socket_options::Congestion_control_strategy_choice::Congestion_control_strategy_choice.`</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span><span class="comment"> *   - Congestion_control_selector::S_ID_TO_STRATEGY_MAP `static` initializer.</span></div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment"> *   - Congestion_control_selector::S_STRATEGY_TO_ID_MAP `static` initializer.</span></div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment"> *   - Factory method Congestion_control_selector::create_strategy().</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span><span class="comment"> *</span></div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span><span class="comment"> * Voila!  You can now use the new congestion control algorithm.</span></div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment"> *</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="comment"> * @todo Tuck away all congestion control-related symbols into new `namespace cong_ctl`?</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"> */</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html">  176</a></span><span class="keyword">class </span><a class="code hl_class" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html">Congestion_control_strategy</a> :</div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span>  <span class="keyword">public</span> <a class="code hl_class" href="classflow_1_1util_1_1Null__interface.html">util::Null_interface</a>,</div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span>  <span class="keyword">public</span> <a class="code hl_class" href="classflow_1_1log_1_1Log__context.html">log::Log_context</a>,</div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span>  <span class="keyword">private</span> boost::noncopyable</div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span>{</div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment"></span> </div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span><span class="comment">   * Returns the maximal number of bytes (with respect to `m_data` field of DATA packets) that this</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span><span class="comment">   * socket should allow to be In-flight at this time.  Bytes, if available, can be sent if and only</span></div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span><span class="comment">   * if this value is greater than the # of In-flight bytes at this time.</span></div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span><span class="comment">   *</span></div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span><span class="comment">   * This is pure.  Each specific congestion control strategy must implement this.</span></div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="comment">   *</span></div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span><span class="comment">   * @note For definition of In-flight bytes, see Peer_socket::m_snd_flying_pkts_by_sent_when.</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="comment">   */</span></div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a2b9a554ac60d9fe9d6faf32433c61c86">  194</a></span>  <span class="keyword">virtual</span> <span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a2b9a554ac60d9fe9d6faf32433c61c86">congestion_window_bytes</a>() <span class="keyword">const</span> = 0;</div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment"></span> </div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment">   * Informs the congestion control strategy that 1 or more previously sent packets whose status was</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment">   * In-flight just received acknowledgments, thus changing their state from In-flight to</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment">   * Acknowledged.  For efficiency and simplicity of behavior, on_acks() should be called as few</span></div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment">   * times as possible while still satisfying the requirement in the previous sentence.  That is,</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment">   * suppose acknowledgments for N packets were received simultaneously.  Then on_acks() must be</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment">   * called one time, with the &quot;packets&quot; argument equal to N -- not, say, N times with `packets == 1`.</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span><span class="comment">   *</span></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span><span class="comment">   * The acknowledgments that led to this on_acks() call also results in 1 or more individual</span></div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span><span class="comment">   * on_individual_ack() calls covering each individual packet.  You MUST call</span></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span><span class="comment">   * on_individual_ack() and THEN call on_acks().</span></div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span><span class="comment">   *</span></div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span><span class="comment">   * If the acknowledgment group that led to on_acks() also exposed the loss of some packets, i.e.,</span></div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span><span class="comment">   * if the criteria for on_loss_event() also hold, then you MUST call on_loss_event() and THEN call</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span><span class="comment">   * on_acks().  (Informal reasoning: the ACKs are exposing drop(s) that occurred in the past,</span></div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span><span class="comment">   * chronologically before the ACKed packets arrived.  Thus the events should fire in that order.)</span></div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span><span class="comment">   *</span></div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span><span class="comment">   * You MUST call on_acks() AFTER Peer_socket state (Peer_socket::m_snd_flying_pkts_by_sent_when et al) has been</span></div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span><span class="comment">   * updated to reflect the acknowledgments being reported here.</span></div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span><span class="comment">   *</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment">   * Assumptions about ACK sender (DATA receiver): It is assumed that:</span></div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment">   *</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment">   *   - Every DATA packet is acknowledged at most T after it was received, where T is some</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment">   *     reasonably small constant time period (see Node::S_DELAYED_ACK_TIMER_PERIOD).  (I.e., an</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment">   *     ACK may be delayed w/r/t DATA reception but only up to a certain delay T.)</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment">   *   - All received but not-yet-acked DATA packets are acknowledged as soon as there are at least</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno">  222</span><span class="comment">   *     Node::S_MAX_FULL_PACKETS_BEFORE_ACK_SEND * max-block-size bytes in the received but</span></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span><span class="comment">   *     not-yet-acked DATA packets.  (I.e., every 2nd DATA packet forces an immediate ACK to be</span></div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span><span class="comment">   *     sent.)</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span><span class="comment">   *   - If, after the DATA receiver has processed all DATA packets that were received</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment">   *     simultaneously, at least one of those DATA packets has a higher sequence number than a</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span><span class="comment">   *     datum the receiver has not yet received, then all received but not-yet-acked DATA packets</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span><span class="comment">   *     are acknowledged.  (I.e., every out-of-order DATA packet forces an immediate ACK to be</span></div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span><span class="comment">   *     sent.)</span></div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span><span class="comment">   *</span></div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment">   * @note congestion_window_bytes() may return a higher value after this call.  You should check</span></div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span><span class="comment">   *       `can_send()`.</span></div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span><span class="comment">   * @note Acknowledgments of data that are not currently In-flight due to being Dropped (a/k/a</span></div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span><span class="comment">   *       late ACKs) or Acknowledged (i.e., duplicate ACKs) must NOT be passed to this method.</span></div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span><span class="comment">   * @note If an acknowledgment for packet P transmission N is received, while packet P transmission</span></div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span><span class="comment">   *       M != N is the one currently In-flight (i.e., packet was retransmitted, but the earlier</span></div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span><span class="comment">   *       incarnation was late-acked), such acknowledgments must NOT be passed to this method.</span></div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span><span class="comment">   *       We may reconsider this in the future.</span></div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span><span class="comment">   * @note on_acks() makes no assumptions about how the reported individual packet acks were</span></div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span><span class="comment">   *       packaged by the ACK sender into actual ACK packets (how many ACKs there were, etc.).</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span><span class="comment">   *       It just assumes every individual acknowledgment is reported to on_acks() as soon as</span></div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno">  242</span><span class="comment">   *       possible and grouped into as few on_acks() calls as possible.</span></div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span><span class="comment">   * @note For definition of In-flight, Acknowledged, and Dropped bytes, see</span></div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span><span class="comment">   *       Peer_socket::m_snd_flying_pkts_by_sent_when and Peer_socket::m_snd_flying_pkts_by_seq_num.</span></div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span><span class="comment">   *</span></div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span><span class="comment">   * @param bytes</span></div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span><span class="comment">   *        The sum of the number of bytes in the user data fields of the packets that have been</span></div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span><span class="comment">   *        Acknowledged.  Must not be zero.</span></div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span><span class="comment">   * @param packets</span></div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span><span class="comment">   *        The number of packets thus Acknowledged.</span></div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span><span class="comment">   */</span></div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno">  252</span>  <span class="keyword">virtual</span> <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a832c2c5f72635ef0d5716a9198fd16d4">on_acks</a>(<span class="keywordtype">size_t</span> bytes, <span class="keywordtype">size_t</span> packets);</div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span><span class="comment"></span> </div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment">   * Informs the congestion control strategy that 1 or more previously sent packets whose status was</span></div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment">   * In-flight have just been inferred to be Dropped by receiving acknowledgments of packets that</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment">   * were sent later than the now-Dropped packets.  For efficiency and simplicity of behavior,</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment">   * on_loss_event() should be called as few times as possible while still satisfying the requirement in</span></div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment">   * the previous sentence.  That is, suppose acknowledgments for N packets were received</span></div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span><span class="comment">   * simultaneously thus exposing M packets as dropped.  Then on_loss_event() must be called one</span></div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno">  261</span><span class="comment">   * time, with the &quot;packets&quot; argument equal to M and not, say, M times with packets == 1.</span></div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span><span class="comment">   *</span></div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span><span class="comment">   * An important addendum to the above rule is as follows.  You MUST NOT call on_loss_event(), if</span></div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span><span class="comment">   * the Dropped packets which would have led to this call are part of the same loss event as those</span></div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span><span class="comment">   * in the preceding on_loss_event() call.  How is &quot;part of the same loss event&quot; defined?  This is</span></div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span><span class="comment">   * formally defined within the large comment header at the top of</span></div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span><span class="comment">   * Node::handle_accumulated_acks().  The informal short version: If the new Dropped</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span><span class="comment">   * packets were sent roughly within an RTT of those in the previous on_loss_event(), then do not</span></div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span><span class="comment">   * call on_loss_event().  The informal reasoning for this is to avoid sharply reducing</span></div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span><span class="comment">   * congestion_window_bytes() value due to 2+ groups of acks that arrive close to each other but</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment">   * really indicate just 1 loss event nevertheless repeatedly reducing CWND.</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span><span class="comment">   *</span></div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span><span class="comment">   * on_loss_event() must be called BEFORE on_individual_ack() and on_acks() are called for the</span></div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment">   * ack group that exposed the lost packets.  See on_acks() and on_individual_ack().</span></div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span><span class="comment">   *</span></div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span><span class="comment">   * You MUST call on_loss_event() AFTER Peer_socket state (`m_snd_flying_pkts_by_sent_when` et al) has been</span></div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span><span class="comment">   * updated to reflect the drops being reported here.</span></div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span><span class="comment">   *</span></div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span><span class="comment">   * @note congestion_window_bytes() WILL NOT return a higher value after this call.  You need not</span></div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span><span class="comment">   *       call `can_send()`.</span></div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span><span class="comment">   * @note For definition of In-flight, Acknowledged, and Dropped bytes, see</span></div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span><span class="comment">   *       Peer_socket::m_snd_flying_pkts_by_sent_when and Peer_socket::m_snd_flying_pkts_by_sent_when.</span></div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span><span class="comment">   * @note This is analogous to the 3-dupe-ACKs part of the Fast Retransmit/Recovery algorithm in</span></div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span><span class="comment">   *       classic TCP congestion control (e.g., RFC 5681).</span></div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno">  285</span><span class="comment">   *</span></div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span><span class="comment">   * @param bytes</span></div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span><span class="comment">   *        The sum of the number of bytes in the user data fields of the packets that have been</span></div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno">  288</span><span class="comment">   *        Dropped.  Must not be zero.</span></div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span><span class="comment">   * @param packets</span></div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno">  290</span><span class="comment">   *        The number of packets thus Dropped.</span></div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment">   */</span></div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span>  <span class="keyword">virtual</span> <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a238eb8f69e309e354d3fbc1c3017f614">on_loss_event</a>(<span class="keywordtype">size_t</span> bytes, <span class="keywordtype">size_t</span> packets);</div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span><span class="comment"></span> </div>
<div class="line"><a id="l00294" name="l00294"></a><span class="lineno">  294</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00295" name="l00295"></a><span class="lineno">  295</span><span class="comment">   * Informs the congestion control strategy that exactly 1 previously sent packet whose status was</span></div>
<div class="line"><a id="l00296" name="l00296"></a><span class="lineno">  296</span><span class="comment">   * In-flight is now known to have the given round trip time (RTT), via acknowledgment.  In other</span></div>
<div class="line"><a id="l00297" name="l00297"></a><span class="lineno">  297</span><span class="comment">   * words, this informs congestion control of each valid individual-packet acknowledgment of a</span></div>
<div class="line"><a id="l00298" name="l00298"></a><span class="lineno">  298</span><span class="comment">   * packet that was In-flight at time of acknowledgment.</span></div>
<div class="line"><a id="l00299" name="l00299"></a><span class="lineno">  299</span><span class="comment">   *</span></div>
<div class="line"><a id="l00300" name="l00300"></a><span class="lineno">  300</span><span class="comment">   * The acknowledgment that led to the given individual RTT measurement also results in a</span></div>
<div class="line"><a id="l00301" name="l00301"></a><span class="lineno">  301</span><span class="comment">   * consolidated on_acks() call that covers that packet and all other packets acked simultaneously;</span></div>
<div class="line"><a id="l00302" name="l00302"></a><span class="lineno">  302</span><span class="comment">   * you MUST call this on_individual_ack() and THEN call on_acks().  on_individual_ack()</span></div>
<div class="line"><a id="l00303" name="l00303"></a><span class="lineno">  303</span><span class="comment">   * should be called in the order of receipt of the containing ACK that led to the RTT measurement;</span></div>
<div class="line"><a id="l00304" name="l00304"></a><span class="lineno">  304</span><span class="comment">   * if two RTTs are generated from one ACK, the tie should be broken in the order of appearance</span></div>
<div class="line"><a id="l00305" name="l00305"></a><span class="lineno">  305</span><span class="comment">   * within the ACK.</span></div>
<div class="line"><a id="l00306" name="l00306"></a><span class="lineno">  306</span><span class="comment">   *</span></div>
<div class="line"><a id="l00307" name="l00307"></a><span class="lineno">  307</span><span class="comment">   * If the acknowledgment group that led to on_individual_ack() also exposed the loss of some packets,</span></div>
<div class="line"><a id="l00308" name="l00308"></a><span class="lineno">  308</span><span class="comment">   * i.e., if the criteria for on_loss_event() also hold, then you MUST call on_loss_event() and</span></div>
<div class="line"><a id="l00309" name="l00309"></a><span class="lineno">  309</span><span class="comment">   * THEN call on_individual_ack().  (Informal reasoning: the ACKs are exposing drop(s) that occurred in the</span></div>
<div class="line"><a id="l00310" name="l00310"></a><span class="lineno">  310</span><span class="comment">   * past, chronologically before the ACKed packets arrived.  Thus the events should fire in that</span></div>
<div class="line"><a id="l00311" name="l00311"></a><span class="lineno">  311</span><span class="comment">   * order.)</span></div>
<div class="line"><a id="l00312" name="l00312"></a><span class="lineno">  312</span><span class="comment">   *</span></div>
<div class="line"><a id="l00313" name="l00313"></a><span class="lineno">  313</span><span class="comment">   * You MUST call on_individual_ack() AFTER Peer_socket state (Peer_socket::m_snd_flying_pkts_by_sent_when</span></div>
<div class="line"><a id="l00314" name="l00314"></a><span class="lineno">  314</span><span class="comment">   * et al) has been updated to reflect the acknowledgments being reported here.</span></div>
<div class="line"><a id="l00315" name="l00315"></a><span class="lineno">  315</span><span class="comment">   *</span></div>
<div class="line"><a id="l00316" name="l00316"></a><span class="lineno">  316</span><span class="comment">   * Assumptions about RTT value: The RTT value is assumed to include only the time spent in transit</span></div>
<div class="line"><a id="l00317" name="l00317"></a><span class="lineno">  317</span><span class="comment">   * from sender to receiver plus the time the ACK spent in transit from receiver to sender.  Any</span></div>
<div class="line"><a id="l00318" name="l00318"></a><span class="lineno">  318</span><span class="comment">   * delay (such as ACK delay) adding to the total time from sending DATA to receiving ACK is *not*</span></div>
<div class="line"><a id="l00319" name="l00319"></a><span class="lineno">  319</span><span class="comment">   * to be included in the RTT.  RTT is meant to measure network conditions/capacity.</span></div>
<div class="line"><a id="l00320" name="l00320"></a><span class="lineno">  320</span><span class="comment">   *</span></div>
<div class="line"><a id="l00321" name="l00321"></a><span class="lineno">  321</span><span class="comment">   * @note congestion_window_bytes() may return a higher value after this call, but you should wait</span></div>
<div class="line"><a id="l00322" name="l00322"></a><span class="lineno">  322</span><span class="comment">   *       to query it until after calling on_acks() for the entire round of acknowledgments being</span></div>
<div class="line"><a id="l00323" name="l00323"></a><span class="lineno">  323</span><span class="comment">   *       handled.</span></div>
<div class="line"><a id="l00324" name="l00324"></a><span class="lineno">  324</span><span class="comment">   * @note Acknowledgments of data that is not currently In-flight due to being Dropped (a/k/a late</span></div>
<div class="line"><a id="l00325" name="l00325"></a><span class="lineno">  325</span><span class="comment">   *       ACKs) or Acknowledged (i.e., duplicate ACKs) must NOT be passed to this method.</span></div>
<div class="line"><a id="l00326" name="l00326"></a><span class="lineno">  326</span><span class="comment">   * @note If an acknowledgment for packet P transmission N is received, while packet P transmission</span></div>
<div class="line"><a id="l00327" name="l00327"></a><span class="lineno">  327</span><span class="comment">   *       M != N is the one currently In-flight (i.e., packet was retransmitted, but the earlier</span></div>
<div class="line"><a id="l00328" name="l00328"></a><span class="lineno">  328</span><span class="comment">   *       incarnation was late-acked), such acknowledgments must NOT be passed to this method.</span></div>
<div class="line"><a id="l00329" name="l00329"></a><span class="lineno">  329</span><span class="comment">   *       We may reconsider this in the future.</span></div>
<div class="line"><a id="l00330" name="l00330"></a><span class="lineno">  330</span><span class="comment">   * @note For definition of In-flight, Acknowledged, and Dropped bytes, see</span></div>
<div class="line"><a id="l00331" name="l00331"></a><span class="lineno">  331</span><span class="comment">   *       Peer_socket::m_snd_flying_pkts_by_sent_when and Peer_socket::m_snd_flying_pkts_by_sent_when.</span></div>
<div class="line"><a id="l00332" name="l00332"></a><span class="lineno">  332</span><span class="comment">   *</span></div>
<div class="line"><a id="l00333" name="l00333"></a><span class="lineno">  333</span><span class="comment">   * @param packet_rtt</span></div>
<div class="line"><a id="l00334" name="l00334"></a><span class="lineno">  334</span><span class="comment">   *        Round trip time of an individual packet.</span></div>
<div class="line"><a id="l00335" name="l00335"></a><span class="lineno">  335</span><span class="comment">   * @param bytes</span></div>
<div class="line"><a id="l00336" name="l00336"></a><span class="lineno">  336</span><span class="comment">   *        The number of bytes of user data corresponding to this RTT sample (i.e., # of bytes</span></div>
<div class="line"><a id="l00337" name="l00337"></a><span class="lineno">  337</span><span class="comment">   *        acknowledged in the acknowledged packet).</span></div>
<div class="line"><a id="l00338" name="l00338"></a><span class="lineno">  338</span><span class="comment">   * @param sent_cwnd_bytes</span></div>
<div class="line"><a id="l00339" name="l00339"></a><span class="lineno">  339</span><span class="comment">   *        congestion_window_bytes() when acked DATA packet was sent.</span></div>
<div class="line"><a id="l00340" name="l00340"></a><span class="lineno">  340</span><span class="comment">   */</span></div>
<div class="line"><a id="l00341" name="l00341"></a><span class="lineno">  341</span>  <span class="keyword">virtual</span> <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#ab5a942e2097cbad4ec8ea152d40ed88a">on_individual_ack</a>(<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow.html#a48799f1263cdeedec125be51a3db2b79">Fine_duration</a>&amp; packet_rtt, <span class="keyword">const</span> <span class="keywordtype">size_t</span> bytes, <span class="keyword">const</span> <span class="keywordtype">size_t</span> sent_cwnd_bytes);</div>
<div class="line"><a id="l00342" name="l00342"></a><span class="lineno">  342</span><span class="comment"></span> </div>
<div class="line"><a id="l00343" name="l00343"></a><span class="lineno">  343</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00344" name="l00344"></a><span class="lineno">  344</span><span class="comment">   * Informs the congestion control strategy that 1 or more previously sent packets whose status was</span></div>
<div class="line"><a id="l00345" name="l00345"></a><span class="lineno">  345</span><span class="comment">   * In-flight have just been inferred to be Dropped because of the Drop Timer expiring.  A formal</span></div>
<div class="line"><a id="l00346" name="l00346"></a><span class="lineno">  346</span><span class="comment">   * description of what &quot;Drop Timer expiring&quot; means is too large to put here, and there are many</span></div>
<div class="line"><a id="l00347" name="l00347"></a><span class="lineno">  347</span><span class="comment">   * different ways to do it.  See class Drop_timer and the code that uses it.  Formally, we expect</span></div>
<div class="line"><a id="l00348" name="l00348"></a><span class="lineno">  348</span><span class="comment">   * that one Drop Timer is running if and only if there is at least one packet In-flight, and that</span></div>
<div class="line"><a id="l00349" name="l00349"></a><span class="lineno">  349</span><span class="comment">   * that Drop Timer expiring implies the immediate conversion of at least one packet from In-flight</span></div>
<div class="line"><a id="l00350" name="l00350"></a><span class="lineno">  350</span><span class="comment">   * to Dropped.  We also expect that, informally, the Drop Timeout indicates serious loss events</span></div>
<div class="line"><a id="l00351" name="l00351"></a><span class="lineno">  351</span><span class="comment">   * and is the 2nd and last resort in detecting loss, the main (and more likely to trigger first)</span></div>
<div class="line"><a id="l00352" name="l00352"></a><span class="lineno">  352</span><span class="comment">   * one being on_loss_event().</span></div>
<div class="line"><a id="l00353" name="l00353"></a><span class="lineno">  353</span><span class="comment">   *</span></div>
<div class="line"><a id="l00354" name="l00354"></a><span class="lineno">  354</span><span class="comment">   * You MUST call on_drop_timeout() AFTER Peer_socket state (Peer_socket::m_snd_flying_pkts_by_sent_when</span></div>
<div class="line"><a id="l00355" name="l00355"></a><span class="lineno">  355</span><span class="comment">   * et al) has been updated to reflect the drops being reported here.</span></div>
<div class="line"><a id="l00356" name="l00356"></a><span class="lineno">  356</span><span class="comment">   *</span></div>
<div class="line"><a id="l00357" name="l00357"></a><span class="lineno">  357</span><span class="comment">   * @note congestion_window_bytes() WILL NOT return a higher value after this call.  You need not</span></div>
<div class="line"><a id="l00358" name="l00358"></a><span class="lineno">  358</span><span class="comment">   *       call `can_send()`.</span></div>
<div class="line"><a id="l00359" name="l00359"></a><span class="lineno">  359</span><span class="comment">   * @note For definition of In-flight, Acknowledged, and Dropped bytes, see</span></div>
<div class="line"><a id="l00360" name="l00360"></a><span class="lineno">  360</span><span class="comment">   *       Peer_socket::m_snd_flying_pkts_by_sent_when and Peer_socket::m_snd_flying_pkts_by_seq_num.</span></div>
<div class="line"><a id="l00361" name="l00361"></a><span class="lineno">  361</span><span class="comment">   * @note This is analogous to the Retransmit Timeout (RTO) algorithm in classic TCP congestion</span></div>
<div class="line"><a id="l00362" name="l00362"></a><span class="lineno">  362</span><span class="comment">   *       control (e.g., RFCs 5681 and 6298).</span></div>
<div class="line"><a id="l00363" name="l00363"></a><span class="lineno">  363</span><span class="comment">   *</span></div>
<div class="line"><a id="l00364" name="l00364"></a><span class="lineno">  364</span><span class="comment">   * @param bytes</span></div>
<div class="line"><a id="l00365" name="l00365"></a><span class="lineno">  365</span><span class="comment">   *        The sum of the number of bytes in the user data fields of the packets that have been</span></div>
<div class="line"><a id="l00366" name="l00366"></a><span class="lineno">  366</span><span class="comment">   *        Dropped with this Drop Timeout.  Must not be zero.</span></div>
<div class="line"><a id="l00367" name="l00367"></a><span class="lineno">  367</span><span class="comment">   * @param packets</span></div>
<div class="line"><a id="l00368" name="l00368"></a><span class="lineno">  368</span><span class="comment">   *        The number of packets thus Dropped.</span></div>
<div class="line"><a id="l00369" name="l00369"></a><span class="lineno">  369</span><span class="comment">   */</span></div>
<div class="line"><a id="l00370" name="l00370"></a><span class="lineno">  370</span>  <span class="keyword">virtual</span> <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#af7543a12c99ea8d31374b064fdf13d2b">on_drop_timeout</a>(<span class="keywordtype">size_t</span> bytes, <span class="keywordtype">size_t</span> packets);</div>
<div class="line"><a id="l00371" name="l00371"></a><span class="lineno">  371</span><span class="comment"></span> </div>
<div class="line"><a id="l00372" name="l00372"></a><span class="lineno">  372</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00373" name="l00373"></a><span class="lineno">  373</span><span class="comment">   * Informs the congestion control strategy that Node considers the connection to be &quot;idle&quot; by</span></div>
<div class="line"><a id="l00374" name="l00374"></a><span class="lineno">  374</span><span class="comment">   * virtue of no desired send activity on the part of the user application for some period of time.</span></div>
<div class="line"><a id="l00375" name="l00375"></a><span class="lineno">  375</span><span class="comment">   * Informally, this means &quot;the user hasn&#39;t wanted to send anything for a while, so you may want to</span></div>
<div class="line"><a id="l00376" name="l00376"></a><span class="lineno">  376</span><span class="comment">   * update your CWND calculations based on that fact, as it&#39;s likely you have obsolete information</span></div>
<div class="line"><a id="l00377" name="l00377"></a><span class="lineno">  377</span><span class="comment">   * about the connection.&quot;  For example, if a connection has been idle for 5 minutes, then there</span></div>
<div class="line"><a id="l00378" name="l00378"></a><span class="lineno">  378</span><span class="comment">   * have been no ACKs for a while, and since ACKs typically are the tool used to gather congestion</span></div>
<div class="line"><a id="l00379" name="l00379"></a><span class="lineno">  379</span><span class="comment">   * data and thus compute CWND, the internal CWND may be reset to its default initial value within</span></div>
<div class="line"><a id="l00380" name="l00380"></a><span class="lineno">  380</span><span class="comment">   * on_idle_timeout().</span></div>
<div class="line"><a id="l00381" name="l00381"></a><span class="lineno">  381</span><span class="comment">   *</span></div>
<div class="line"><a id="l00382" name="l00382"></a><span class="lineno">  382</span><span class="comment">   * The formal definition of Idle Timeout is the one used in Node::send_worker().  Short version:</span></div>
<div class="line"><a id="l00383" name="l00383"></a><span class="lineno">  383</span><span class="comment">   * an Idle Timeout occurs T after the last packet to be sent out, where T is the Drop Timeout (see</span></div>
<div class="line"><a id="l00384" name="l00384"></a><span class="lineno">  384</span><span class="comment">   * on_drop_timeout()).</span></div>
<div class="line"><a id="l00385" name="l00385"></a><span class="lineno">  385</span><span class="comment">   *</span></div>
<div class="line"><a id="l00386" name="l00386"></a><span class="lineno">  386</span><span class="comment">   * @note congestion_window_bytes() WILL NOT return a higher value after this call.  You need not</span></div>
<div class="line"><a id="l00387" name="l00387"></a><span class="lineno">  387</span><span class="comment">   *       call `can_send()`.</span></div>
<div class="line"><a id="l00388" name="l00388"></a><span class="lineno">  388</span><span class="comment">   * @note This is analogous to the &quot;Restarting Idle Connections&quot; algorithm in classic TCP</span></div>
<div class="line"><a id="l00389" name="l00389"></a><span class="lineno">  389</span><span class="comment">   *       congestion control (RFC 5681-4.1).</span></div>
<div class="line"><a id="l00390" name="l00390"></a><span class="lineno">  390</span><span class="comment">   */</span></div>
<div class="line"><a id="l00391" name="l00391"></a><span class="lineno">  391</span>  <span class="keyword">virtual</span> <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a6cecbb76a9e837824c0b820e7cc1b3b7">on_idle_timeout</a>();</div>
<div class="line"><a id="l00392" name="l00392"></a><span class="lineno">  392</span> </div>
<div class="line"><a id="l00393" name="l00393"></a><span class="lineno">  393</span><span class="keyword">protected</span>:</div>
<div class="line"><a id="l00394" name="l00394"></a><span class="lineno">  394</span><span class="comment"></span> </div>
<div class="line"><a id="l00395" name="l00395"></a><span class="lineno">  395</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00396" name="l00396"></a><span class="lineno">  396</span><span class="comment">   * Constructs object by setting up logging and saving a pointer to the containing Peer_socket.</span></div>
<div class="line"><a id="l00397" name="l00397"></a><span class="lineno">  397</span><span class="comment">   * Only a weak pointer of `sock` is stored: the `shared_ptr` itself is not saved, so the reference</span></div>
<div class="line"><a id="l00398" name="l00398"></a><span class="lineno">  398</span><span class="comment">   * count of `sock` does not increase.  This avoids a circular `shared_ptr` situation.</span></div>
<div class="line"><a id="l00399" name="l00399"></a><span class="lineno">  399</span><span class="comment">   *</span></div>
<div class="line"><a id="l00400" name="l00400"></a><span class="lineno">  400</span><span class="comment">   * @param logger_ptr</span></div>
<div class="line"><a id="l00401" name="l00401"></a><span class="lineno">  401</span><span class="comment">   *        The Logger implementation to use subsequently.</span></div>
<div class="line"><a id="l00402" name="l00402"></a><span class="lineno">  402</span><span class="comment">   * @param sock</span></div>
<div class="line"><a id="l00403" name="l00403"></a><span class="lineno">  403</span><span class="comment">   *        The Peer_socket for which this module will control congestion policy.</span></div>
<div class="line"><a id="l00404" name="l00404"></a><span class="lineno">  404</span><span class="comment">   */</span></div>
<div class="line"><a id="l00405" name="l00405"></a><span class="lineno">  405</span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a0eacd984fd4e7d5ad3c30a59082ac95b">Congestion_control_strategy</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock);</div>
<div class="line"><a id="l00406" name="l00406"></a><span class="lineno">  406</span><span class="comment"></span> </div>
<div class="line"><a id="l00407" name="l00407"></a><span class="lineno">  407</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00408" name="l00408"></a><span class="lineno">  408</span><span class="comment">   * Utility for subclasses that returns a handle to the containing Peer_socket.  If somehow the</span></div>
<div class="line"><a id="l00409" name="l00409"></a><span class="lineno">  409</span><span class="comment">   * containing Peer_socket has been deleted, `assert()` trips.</span></div>
<div class="line"><a id="l00410" name="l00410"></a><span class="lineno">  410</span><span class="comment">   *</span></div>
<div class="line"><a id="l00411" name="l00411"></a><span class="lineno">  411</span><span class="comment">   * @return Ditto.</span></div>
<div class="line"><a id="l00412" name="l00412"></a><span class="lineno">  412</span><span class="comment">   */</span></div>
<div class="line"><a id="l00413" name="l00413"></a><span class="lineno">  413</span>  <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a3e9786f9e5f170ca23135a2a815bc3f4">socket</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00414" name="l00414"></a><span class="lineno">  414</span> </div>
<div class="line"><a id="l00415" name="l00415"></a><span class="lineno">  415</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00416" name="l00416"></a><span class="lineno">  416</span> </div>
<div class="line"><a id="l00417" name="l00417"></a><span class="lineno">  417</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00418" name="l00418"></a><span class="lineno">  418</span><span class="comment"></span> </div>
<div class="line"><a id="l00419" name="l00419"></a><span class="lineno">  419</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00420" name="l00420"></a><span class="lineno">  420</span><span class="comment">   * The containing socket (read-only access).  Implementation may rely on various state stored</span></div>
<div class="line"><a id="l00421" name="l00421"></a><span class="lineno">  421</span><span class="comment">   * inside the pointed-to Peer_socket.</span></div>
<div class="line"><a id="l00422" name="l00422"></a><span class="lineno">  422</span><span class="comment">   *</span></div>
<div class="line"><a id="l00423" name="l00423"></a><span class="lineno">  423</span><span class="comment">   * Why `weak_ptr`?  If we stored a `shared_ptr` (Peer_socket::Const_ptr) then something would have to</span></div>
<div class="line"><a id="l00424" name="l00424"></a><span class="lineno">  424</span><span class="comment">   * delete this Congestion_control_strategy object before the pointee Peer_socket&#39;s ref-count could</span></div>
<div class="line"><a id="l00425" name="l00425"></a><span class="lineno">  425</span><span class="comment">   * drop to zero and it too could be deleted; this is undesirable since the guy that would want to</span></div>
<div class="line"><a id="l00426" name="l00426"></a><span class="lineno">  426</span><span class="comment">   * delete this Congestion_control_strategy is Peer_socket&#39;s destructor itself (standard circular</span></div>
<div class="line"><a id="l00427" name="l00427"></a><span class="lineno">  427</span><span class="comment">   * `shared_ptr` problem).  If we stored a raw const `Peer_socket*` pointer instead, that would be</span></div>
<div class="line"><a id="l00428" name="l00428"></a><span class="lineno">  428</span><span class="comment">   * fine.  However, using a `weak_ptr` allows us to `assert()` in a civilized way if the underlying</span></div>
<div class="line"><a id="l00429" name="l00429"></a><span class="lineno">  429</span><span class="comment">   * Peer_socket had been deleted (instead of crashing due to accessing deleted memory as we would</span></div>
<div class="line"><a id="l00430" name="l00430"></a><span class="lineno">  430</span><span class="comment">   * with a raw pointer).  This isn&#39;t really a big deal, since hopefully our code will be written</span></div>
<div class="line"><a id="l00431" name="l00431"></a><span class="lineno">  431</span><span class="comment">   * properly to avoid this, but this is just a little cleaner.</span></div>
<div class="line"><a id="l00432" name="l00432"></a><span class="lineno">  432</span><span class="comment">   */</span></div>
<div class="line"><a id="l00433" name="l00433"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a1da6833e0c23d111432cbdd3f5451180">  433</a></span>  boost::weak_ptr&lt;Peer_socket::Const_ptr::element_type&gt; <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a1da6833e0c23d111432cbdd3f5451180">m_sock</a>;</div>
<div class="line"><a id="l00434" name="l00434"></a><span class="lineno">  434</span>}; <span class="comment">// class Congestion_control_strategy</span></div>
<div class="line"><a id="l00435" name="l00435"></a><span class="lineno">  435</span><span class="comment"></span> </div>
<div class="line"><a id="l00436" name="l00436"></a><span class="lineno">  436</span><span class="comment">/**</span></div>
<div class="line"><a id="l00437" name="l00437"></a><span class="lineno">  437</span><span class="comment"> * Namespace-like class that enables an `enum`-based selection of the Congestion_control_strategy</span></div>
<div class="line"><a id="l00438" name="l00438"></a><span class="lineno">  438</span><span class="comment"> * interface implementation to use for a given socket (for programmatic socket options) and</span></div>
<div class="line"><a id="l00439" name="l00439"></a><span class="lineno">  439</span><span class="comment"> * facilitates stream I/O of these enums (allowing parsing and outputting these socket options).</span></div>
<div class="line"><a id="l00440" name="l00440"></a><span class="lineno">  440</span><span class="comment"> *</span></div>
<div class="line"><a id="l00441" name="l00441"></a><span class="lineno">  441</span><span class="comment"> * ### Provided facilities ###</span></div>
<div class="line"><a id="l00442" name="l00442"></a><span class="lineno">  442</span><span class="comment"> *   - Create Congestion_control_strategy subclass instance based on `enum` value;</span></div>
<div class="line"><a id="l00443" name="l00443"></a><span class="lineno">  443</span><span class="comment"> *   - Return set of possible text IDs, each representing a distinct `enum` value;</span></div>
<div class="line"><a id="l00444" name="l00444"></a><span class="lineno">  444</span><span class="comment"> *   - Read such an ID from an `istream` into an `enum` value; write an ID from an `enum` value to an `ostream`.</span></div>
<div class="line"><a id="l00445" name="l00445"></a><span class="lineno">  445</span><span class="comment"> */</span></div>
<div class="line"><a id="l00446" name="l00446"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__selector.html">  446</a></span><span class="keyword">class </span><a class="code hl_class" href="classflow_1_1net__flow_1_1Congestion__control__selector.html">Congestion_control_selector</a> :</div>
<div class="line"><a id="l00447" name="l00447"></a><span class="lineno">  447</span>  <span class="keyword">private</span> boost::noncopyable</div>
<div class="line"><a id="l00448" name="l00448"></a><span class="lineno">  448</span>{</div>
<div class="line"><a id="l00449" name="l00449"></a><span class="lineno">  449</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00450" name="l00450"></a><span class="lineno">  450</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00451" name="l00451"></a><span class="lineno">  451</span><span class="comment"></span> </div>
<div class="line"><a id="l00452" name="l00452"></a><span class="lineno">  452</span><span class="comment">  /// Short-hand for Peer_socket_options::Congestion_control_strategy.</span></div>
<div class="line"><a id="l00453" name="l00453"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#acb937e24cf041aa15c5e92c2550ac4ec">  453</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_enumeration" href="structflow_1_1net__flow_1_1Peer__socket__options.html#a42ce94dbc5d8be28134261c2eb18b245">Strategy_choice</a> = <a class="code hl_enumeration" href="structflow_1_1net__flow_1_1Peer__socket__options.html#a42ce94dbc5d8be28134261c2eb18b245">Peer_socket_options::Congestion_control_strategy_choice</a>;</div>
<div class="line"><a id="l00454" name="l00454"></a><span class="lineno">  454</span> </div>
<div class="line"><a id="l00455" name="l00455"></a><span class="lineno">  455</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00456" name="l00456"></a><span class="lineno">  456</span><span class="comment"></span> </div>
<div class="line"><a id="l00457" name="l00457"></a><span class="lineno">  457</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00458" name="l00458"></a><span class="lineno">  458</span><span class="comment">   * Factory method that, given an `enum` identifying the desired strategy, allocates the appropriate</span></div>
<div class="line"><a id="l00459" name="l00459"></a><span class="lineno">  459</span><span class="comment">   * Congestion_control_strategy subclass instance on the heap and returns a pointer to it.</span></div>
<div class="line"><a id="l00460" name="l00460"></a><span class="lineno">  460</span><span class="comment">   *</span></div>
<div class="line"><a id="l00461" name="l00461"></a><span class="lineno">  461</span><span class="comment">   * @param strategy_choice</span></div>
<div class="line"><a id="l00462" name="l00462"></a><span class="lineno">  462</span><span class="comment">   *        The type of strategy (congestion control algorithm) to use.</span></div>
<div class="line"><a id="l00463" name="l00463"></a><span class="lineno">  463</span><span class="comment">   * @param logger_ptr</span></div>
<div class="line"><a id="l00464" name="l00464"></a><span class="lineno">  464</span><span class="comment">   *        The Logger implementation to use subsequently.</span></div>
<div class="line"><a id="l00465" name="l00465"></a><span class="lineno">  465</span><span class="comment">   * @param sock</span></div>
<div class="line"><a id="l00466" name="l00466"></a><span class="lineno">  466</span><span class="comment">   *        The Peer_socket for which this module will control congestion policy.</span></div>
<div class="line"><a id="l00467" name="l00467"></a><span class="lineno">  467</span><span class="comment">   * @return Pointer to newly allocated instance.</span></div>
<div class="line"><a id="l00468" name="l00468"></a><span class="lineno">  468</span><span class="comment">   */</span></div>
<div class="line"><a id="l00469" name="l00469"></a><span class="lineno">  469</span>  <span class="keyword">static</span> <a class="code hl_class" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html">Congestion_control_strategy</a>* <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a52eee18d41c3f9cc7d6c48b766a7919f">create_strategy</a>(<a class="code hl_enumeration" href="structflow_1_1net__flow_1_1Peer__socket__options.html#a42ce94dbc5d8be28134261c2eb18b245">Strategy_choice</a> strategy_choice,</div>
<div class="line"><a id="l00470" name="l00470"></a><span class="lineno">  470</span>                                                      <a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock);</div>
<div class="line"><a id="l00471" name="l00471"></a><span class="lineno">  471</span><span class="comment"></span> </div>
<div class="line"><a id="l00472" name="l00472"></a><span class="lineno">  472</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00473" name="l00473"></a><span class="lineno">  473</span><span class="comment">   * Returns a list of strings, called IDs, each of which textually represents a distinct</span></div>
<div class="line"><a id="l00474" name="l00474"></a><span class="lineno">  474</span><span class="comment">   * Congestion_control_strategy subclass.  You can output this in socket option help text as the</span></div>
<div class="line"><a id="l00475" name="l00475"></a><span class="lineno">  475</span><span class="comment">   * possible choices for congestion control strategy.  They will match the possible text inputs to</span></div>
<div class="line"><a id="l00476" name="l00476"></a><span class="lineno">  476</span><span class="comment">   * `operator&gt;&gt;(istream&amp;, Strategy_choice&amp;)`.</span></div>
<div class="line"><a id="l00477" name="l00477"></a><span class="lineno">  477</span><span class="comment">   *</span></div>
<div class="line"><a id="l00478" name="l00478"></a><span class="lineno">  478</span><span class="comment">   * @param ids</span></div>
<div class="line"><a id="l00479" name="l00479"></a><span class="lineno">  479</span><span class="comment">   *        The `vector` of strings to clear and fill with the above.</span></div>
<div class="line"><a id="l00480" name="l00480"></a><span class="lineno">  480</span><span class="comment">   */</span></div>
<div class="line"><a id="l00481" name="l00481"></a><span class="lineno">  481</span>  <span class="keyword">static</span> <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#aca9ae5272088f3ef8fb81f40cc85224c">get_ids</a>(std::vector&lt;std::string&gt;* ids);</div>
<div class="line"><a id="l00482" name="l00482"></a><span class="lineno">  482</span> </div>
<div class="line"><a id="l00483" name="l00483"></a><span class="lineno">  483</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00484" name="l00484"></a><span class="lineno">  484</span>  <span class="comment">// Friends.</span></div>
<div class="line"><a id="l00485" name="l00485"></a><span class="lineno">  485</span> </div>
<div class="line"><a id="l00486" name="l00486"></a><span class="lineno">  486</span>  <span class="comment">// Friend of Congestion_control_selector: For access to Congestion_control_selector::S_ID_TO_STRATEGY_MAP and so on.</span></div>
<div class="line"><a id="l00487" name="l00487"></a><span class="lineno">  487</span>  <span class="keyword">friend</span> std::istream&amp; <a class="code hl_friend" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#aa4e29e3faa67810804c3053b8ed33380">operator&gt;&gt;</a>(std::istream&amp; is,</div>
<div class="line"><a id="l00488" name="l00488"></a><span class="lineno">  488</span>                                  <a class="code hl_enumeration" href="structflow_1_1net__flow_1_1Peer__socket__options.html#a42ce94dbc5d8be28134261c2eb18b245">Congestion_control_selector::Strategy_choice</a>&amp; strategy_choice);</div>
<div class="line"><a id="l00489" name="l00489"></a><span class="lineno">  489</span>  <span class="comment">// Friend of Congestion_control_selector: For access to Congestion_control_selector::S_STRATEGY_TO_ID_MAP and so on.</span></div>
<div class="line"><a id="l00490" name="l00490"></a><span class="lineno">  490</span>  <span class="keyword">friend</span> std::ostream&amp; <a class="code hl_friend" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a0b2749c14e5458e40eb2d40d0d4f1144">operator&lt;&lt;</a>(std::ostream&amp; os,</div>
<div class="line"><a id="l00491" name="l00491"></a><span class="lineno">  491</span>                                  <span class="keyword">const</span> <a class="code hl_enumeration" href="structflow_1_1net__flow_1_1Peer__socket__options.html#a42ce94dbc5d8be28134261c2eb18b245">Congestion_control_selector::Strategy_choice</a>&amp; strategy_choice);</div>
<div class="line"><a id="l00492" name="l00492"></a><span class="lineno">  492</span> </div>
<div class="line"><a id="l00493" name="l00493"></a><span class="lineno">  493</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00494" name="l00494"></a><span class="lineno">  494</span><span class="comment"></span> </div>
<div class="line"><a id="l00495" name="l00495"></a><span class="lineno">  495</span><span class="comment">  /// Maps each ID to the corresponding #Strategy_choice `enum` value.</span></div>
<div class="line"><a id="l00496" name="l00496"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#aaa68a02633d67e11bdf7e8e722370ca2">  496</a></span><span class="comment"></span>  <span class="keyword">static</span> <span class="keyword">const</span> std::map&lt;std::string, Strategy_choice&gt; <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#aaa68a02633d67e11bdf7e8e722370ca2">S_ID_TO_STRATEGY_MAP</a>;<span class="comment"></span></div>
<div class="line"><a id="l00497" name="l00497"></a><span class="lineno">  497</span><span class="comment">  /// The inverse of #S_ID_TO_STRATEGY_MAP.</span></div>
<div class="line"><a id="l00498" name="l00498"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a590c0877dd8751b190173ed9f01d23c7">  498</a></span><span class="comment"></span>  <span class="keyword">static</span> <span class="keyword">const</span> std::map&lt;Strategy_choice, std::string&gt; <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a590c0877dd8751b190173ed9f01d23c7">S_STRATEGY_TO_ID_MAP</a>;</div>
<div class="line"><a id="l00499" name="l00499"></a><span class="lineno">  499</span> </div>
<div class="line"><a id="l00500" name="l00500"></a><span class="lineno">  500</span>  <span class="comment">// Privacy stubs.</span></div>
<div class="line"><a id="l00501" name="l00501"></a><span class="lineno">  501</span><span class="comment"></span> </div>
<div class="line"><a id="l00502" name="l00502"></a><span class="lineno">  502</span><span class="comment">  /// Forbid all instantiation.</span></div>
<div class="line"><a id="l00503" name="l00503"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a3b71a9061f48a6ce57e4acd29328f67a">  503</a></span><span class="comment"></span>  <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a3b71a9061f48a6ce57e4acd29328f67a">Congestion_control_selector</a>() = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00504" name="l00504"></a><span class="lineno">  504</span>}; <span class="comment">// class Congestion_control_selector</span></div>
<div class="line"><a id="l00505" name="l00505"></a><span class="lineno">  505</span> </div>
<div class="line"><a id="l00506" name="l00506"></a><span class="lineno">  506</span>} <span class="comment">// namespace flow::net_flow</span></div>
<div class="ttc" id="aclassflow_1_1log_1_1Log__context_html"><div class="ttname"><a href="classflow_1_1log_1_1Log__context.html">flow::log::Log_context</a></div><div class="ttdoc">Convenience class that simply stores a Logger and/or Component passed into a constructor; and returns...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01609">log.hpp:1610</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Logger_html"><div class="ttname"><a href="classflow_1_1log_1_1Logger.html">flow::log::Logger</a></div><div class="ttdoc">Interface that the user should implement, passing the implementing Logger into logging classes (Flow'...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01280">log.hpp:1284</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html">flow::net_flow::Congestion_control_selector</a></div><div class="ttdoc">Namespace-like class that enables an enum-based selection of the Congestion_control_strategy interfac...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8hpp_source.html#l00446">cong_ctl.hpp:448</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html_a0b2749c14e5458e40eb2d40d0d4f1144"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a0b2749c14e5458e40eb2d40d0d4f1144">flow::net_flow::Congestion_control_selector::operator&lt;&lt;</a></div><div class="ttdeci">friend std::ostream &amp; operator&lt;&lt;(std::ostream &amp;os, const Congestion_control_selector::Strategy_choice &amp;strategy_choice)</div><div class="ttdoc">Serializes a Peer_socket_options::Congestion_control_strategy_choice enum to a standard ostream – the...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00146">cong_ctl.cpp:146</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html_a3b71a9061f48a6ce57e4acd29328f67a"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a3b71a9061f48a6ce57e4acd29328f67a">flow::net_flow::Congestion_control_selector::Congestion_control_selector</a></div><div class="ttdeci">Congestion_control_selector()=delete</div><div class="ttdoc">Forbid all instantiation.</div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html_a52eee18d41c3f9cc7d6c48b766a7919f"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a52eee18d41c3f9cc7d6c48b766a7919f">flow::net_flow::Congestion_control_selector::create_strategy</a></div><div class="ttdeci">static Congestion_control_strategy * create_strategy(Strategy_choice strategy_choice, log::Logger *logger_ptr, Peer_socket::Const_ptr sock)</div><div class="ttdoc">Factory method that, given an enum identifying the desired strategy, allocates the appropriate Conges...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00100">cong_ctl.cpp:101</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html_a590c0877dd8751b190173ed9f01d23c7"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html#a590c0877dd8751b190173ed9f01d23c7">flow::net_flow::Congestion_control_selector::S_STRATEGY_TO_ID_MAP</a></div><div class="ttdeci">static const std::map&lt; Strategy_choice, std::string &gt; S_STRATEGY_TO_ID_MAP</div><div class="ttdoc">The inverse of S_ID_TO_STRATEGY_MAP.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8hpp_source.html#l00498">cong_ctl.hpp:498</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html_aa4e29e3faa67810804c3053b8ed33380"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html#aa4e29e3faa67810804c3053b8ed33380">flow::net_flow::Congestion_control_selector::operator&gt;&gt;</a></div><div class="ttdeci">friend std::istream &amp; operator&gt;&gt;(std::istream &amp;is, Congestion_control_selector::Strategy_choice &amp;strategy_choice)</div><div class="ttdoc">Deserializes a Peer_socket_options::Congestion_control_strategy_choice enum from a standard input str...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00124">cong_ctl.cpp:124</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html_aaa68a02633d67e11bdf7e8e722370ca2"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html#aaa68a02633d67e11bdf7e8e722370ca2">flow::net_flow::Congestion_control_selector::S_ID_TO_STRATEGY_MAP</a></div><div class="ttdeci">static const std::map&lt; std::string, Strategy_choice &gt; S_ID_TO_STRATEGY_MAP</div><div class="ttdoc">Maps each ID to the corresponding Strategy_choice enum value.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8hpp_source.html#l00496">cong_ctl.hpp:496</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__selector_html_aca9ae5272088f3ef8fb81f40cc85224c"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__selector.html#aca9ae5272088f3ef8fb81f40cc85224c">flow::net_flow::Congestion_control_selector::get_ids</a></div><div class="ttdeci">static void get_ids(std::vector&lt; std::string &gt; *ids)</div><div class="ttdoc">Returns a list of strings, called IDs, each of which textually represents a distinct Congestion_contr...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00115">cong_ctl.cpp:115</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html">flow::net_flow::Congestion_control_strategy</a></div><div class="ttdoc">The abstract interface for a per-socket module that determines the socket's congestion control behavi...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8hpp_source.html#l00176">cong_ctl.hpp:180</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a0eacd984fd4e7d5ad3c30a59082ac95b"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a0eacd984fd4e7d5ad3c30a59082ac95b">flow::net_flow::Congestion_control_strategy::Congestion_control_strategy</a></div><div class="ttdeci">Congestion_control_strategy(log::Logger *logger_ptr, Peer_socket::Const_ptr sock)</div><div class="ttdoc">Constructs object by setting up logging and saving a pointer to the containing Peer_socket.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00029">cong_ctl.cpp:29</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a1da6833e0c23d111432cbdd3f5451180"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a1da6833e0c23d111432cbdd3f5451180">flow::net_flow::Congestion_control_strategy::m_sock</a></div><div class="ttdeci">boost::weak_ptr&lt; Peer_socket::Const_ptr::element_type &gt; m_sock</div><div class="ttdoc">The containing socket (read-only access).</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8hpp_source.html#l00433">cong_ctl.hpp:433</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a238eb8f69e309e354d3fbc1c3017f614"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a238eb8f69e309e354d3fbc1c3017f614">flow::net_flow::Congestion_control_strategy::on_loss_event</a></div><div class="ttdeci">virtual void on_loss_event(size_t bytes, size_t packets)</div><div class="ttdoc">Informs the congestion control strategy that 1 or more previously sent packets whose status was In-fl...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00041">cong_ctl.cpp:41</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a2b9a554ac60d9fe9d6faf32433c61c86"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a2b9a554ac60d9fe9d6faf32433c61c86">flow::net_flow::Congestion_control_strategy::congestion_window_bytes</a></div><div class="ttdeci">virtual size_t congestion_window_bytes() const =0</div><div class="ttdoc">Returns the maximal number of bytes (with respect to m_data field of DATA packets) that this socket s...</div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a3e9786f9e5f170ca23135a2a815bc3f4"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a3e9786f9e5f170ca23135a2a815bc3f4">flow::net_flow::Congestion_control_strategy::socket</a></div><div class="ttdeci">Peer_socket::Const_ptr socket() const</div><div class="ttdoc">Utility for subclasses that returns a handle to the containing Peer_socket.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00063">cong_ctl.cpp:63</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a6cecbb76a9e837824c0b820e7cc1b3b7"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a6cecbb76a9e837824c0b820e7cc1b3b7">flow::net_flow::Congestion_control_strategy::on_idle_timeout</a></div><div class="ttdeci">virtual void on_idle_timeout()</div><div class="ttdoc">Informs the congestion control strategy that Node considers the connection to be &quot;idle&quot; by virtue of ...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00053">cong_ctl.cpp:53</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a832c2c5f72635ef0d5716a9198fd16d4"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a832c2c5f72635ef0d5716a9198fd16d4">flow::net_flow::Congestion_control_strategy::on_acks</a></div><div class="ttdeci">virtual void on_acks(size_t bytes, size_t packets)</div><div class="ttdoc">Informs the congestion control strategy that 1 or more previously sent packets whose status was In-fl...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00036">cong_ctl.cpp:36</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_ab5a942e2097cbad4ec8ea152d40ed88a"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#ab5a942e2097cbad4ec8ea152d40ed88a">flow::net_flow::Congestion_control_strategy::on_individual_ack</a></div><div class="ttdeci">virtual void on_individual_ack(const Fine_duration &amp;packet_rtt, const size_t bytes, const size_t sent_cwnd_bytes)</div><div class="ttdoc">Informs the congestion control strategy that exactly 1 previously sent packet whose status was In-fli...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00058">cong_ctl.cpp:58</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_af7543a12c99ea8d31374b064fdf13d2b"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#af7543a12c99ea8d31374b064fdf13d2b">flow::net_flow::Congestion_control_strategy::on_drop_timeout</a></div><div class="ttdeci">virtual void on_drop_timeout(size_t bytes, size_t packets)</div><div class="ttdoc">Informs the congestion control strategy that 1 or more previously sent packets whose status was In-fl...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00047">cong_ctl.cpp:47</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Null__interface_html"><div class="ttname"><a href="classflow_1_1util_1_1Null__interface.html">flow::util::Null_interface</a></div><div class="ttdoc">An empty interface, consisting of nothing but a default virtual destructor, intended as a boiler-plat...</div><div class="ttdef"><b>Definition:</b> <a href="util_2util_8hpp_source.html#l00044">util.hpp:45</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Shared__ptr__alias__holder_html_aef7998db71c60eeb5d1e3d1a97c14886"><div class="ttname"><a href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">flow::util::Shared_ptr_alias_holder&lt; boost::shared_ptr&lt; Peer_socket &gt; &gt;::Const_ptr</a></div><div class="ttdeci">Const_target_ptr Const_ptr</div><div class="ttdoc">Short-hand for ref-counted pointer to immutable values of type Target_type::element_type (a-la T cons...</div><div class="ttdef"><b>Definition:</b> <a href="shared__ptr__alias__holder_8hpp_source.html#l00127">shared_ptr_alias_holder.hpp:127</a></div></div>
<div class="ttc" id="adetail_2net__flow__fwd_8hpp_html"><div class="ttname"><a href="detail_2net__flow__fwd_8hpp.html">net_flow_fwd.hpp</a></div></div>
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<div class="ttc" id="anamespaceflow_1_1net__flow_html"><div class="ttname"><a href="namespaceflow_1_1net__flow.html">flow::net_flow</a></div><div class="ttdoc">Flow module containing the API and implementation of the Flow network protocol, a TCP-inspired stream...</div><div class="ttdef"><b>Definition:</b> <a href="asio_2node_8cpp_source.html#l00024">node.cpp:25</a></div></div>
<div class="ttc" id="anamespaceflow_html_a48799f1263cdeedec125be51a3db2b79"><div class="ttname"><a href="namespaceflow.html#a48799f1263cdeedec125be51a3db2b79">flow::Fine_duration</a></div><div class="ttdeci">Fine_clock::duration Fine_duration</div><div class="ttdoc">A high-res time duration as computed from two Fine_time_pts.</div><div class="ttdef"><b>Definition:</b> <a href="common_8hpp_source.html#l00416">common.hpp:416</a></div></div>
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<div class="ttc" id="astructflow_1_1net__flow_1_1Peer__socket__options_html_a42ce94dbc5d8be28134261c2eb18b245"><div class="ttname"><a href="structflow_1_1net__flow_1_1Peer__socket__options.html#a42ce94dbc5d8be28134261c2eb18b245">flow::net_flow::Peer_socket_options::Congestion_control_strategy_choice</a></div><div class="ttdeci">Congestion_control_strategy_choice</div><div class="ttdoc">The possible choices for congestion control strategy for the socket.</div><div class="ttdef"><b>Definition:</b> <a href="options_8hpp_source.html#l00062">options.hpp:63</a></div></div>
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